Drouot and Vanderkindere listed the three items — including one jewel-encrusted skull of an Arab slaver killed in 1893 — alongside paintings, coats, and other antiques.

The skulls date back to Belgium’s period of colonization in Africa. An estimated 10 million people died as a result of Belgian expansion, with the Congo in particular being subject to widespread violence.

The Arab skull of Munie Mohara, a chieftain slaver, was believed to have been taken as a prize by Belgian steelers following his death.

Earlier this year Belgium passed a law to return looted artifacts to the Congo. A government committee was expected to propose the return of human remains held in the European country.

Following the sale delisting, the auction house said: “We in no way support the suffering and humiliation that people were subjected to during the colonial period. We apologize to anyone who feels hurt by this sale.”

Colonial Memory and the Fight Against Discrimination, a campaign group, filed a complaint over the auction.

The group’s co-coordinator, Genevieve Kaninda, said: “It is as if people are being killed a second time. The colonial violence keeps repeating itself.”